From the Los Angeles Times:
Canadian sites look overseas for drug supply
Millions of Americans now buy drugs from Canadian-based Internet pharmacies in an effort to save money. So far, the quantity and quality of the drugs has seemed relatively assured.

But during the last year, U.S. customers using Canadian websites have faced increasing difficulty getting top-selling medications such as Celebrex to treat arthritis and the antidepressant Effexor. That's because several of the world's biggest pharmaceutical makers are restricting supply to online Canadian pharmacies that ship to the U.S., leading to delays of several weeks for many customers. In severe cases, some sites have stopped accepting new clients looking for the hardest-to-get medications.